Modern vehicles use a large number of electronics, motors, heaters, and other electrically-driven equipment. Electric motors, in particular, are ubiquitous in modern vehicles, including aircraft, and drive everything from hydraulic pumps to cabin fans. Conventionally, each of these electric motors is driven by an independent motor controller. Each motor controller is sized to be able to carry the maximum amount of current required to power its respective motor at full power for an extended period of time (and generally, further includes some additional capacity for safety) without overheating or malfunctioning.
As a result, each aircraft carries a number of motor controllers, each of which is typically oversized and underutilized a majority of the time. In other words, the motor controller includes enough capacity to run the motor at full power for an extended period of time plus a safety margin, but motors are rarely, if ever, run at full capacity. This is because the motors themselves have some safety margin built in and because, a majority of the time, the motors are operating in a lower demand regime (e.g., the cabin fan is not always on “High”). In addition, some motors are only used occasionally, or during specific flight segments, and are unused the remainder of the time. As a result, many of an aircraft's complement of heavy, expensive motor controllers spend a majority of their service life either inactive or operating significantly below their rated power outputs.
To better utilize motor controller capacity, a modular converter system can provide multiple, modular, assignable, dynamically reconfigurable motor controllers that can work alone or in parallel with other parallel motor controllers to meet power control needs. The converter system connects one or more controllers, connected in parallel, to each active electrical load in the aircraft, as necessary, to meet existing power demands. Increasing utilization of motor controllers can provide a corresponding reduction in system weight and cost.
During operation the modular converter system, a plurality of paralleled inverters can operate in parallel to power an electric motor or another electrical load. However, the loading of the paralleled inverters can vary due to manufacturing tolerances and variations of the inverters, as well as parasitic elements caused by wiring resistance and inductance and/or other connected components. As a result, driving the paralleled inverters with the same drive signals can result in uneven loading. While the current from each of the paralleled inverters can be balanced using inductors at the outputs, these inductors tend to be unsuitably large and lossy when used within high-power applications.